Two compartment refrigerator



2 heets-Sheet 1 Aug. 9 19 .d m m m n n WWO m w MJ MM n m h m %L Y B\\\\\0\ Q 5 w 3 Their Attorney y 21, 1957 J; M. MURPHY ETAL 2,792,691

TWO COMPARTMENT REFRIGERATOR Filed Aug. 9, 1955 2 Sheets-Sheet 2 INVENTOR.

John M. M r hy and By Leonard J. ann

Their Aflomgy lF/g TWO COMPARTMENT REFRHGERATUR John M. Murphy andLeonard 5. Mann, Dayton, tiihio, assignors to General Motors@orporation, Detroit, Mich., a corporation of Delaware ApplicationAugust 9, 1955, Serial No. 527,2%

12 Claims. (Cl. 62--4) This invention is directed to refrigeratingapparatus and more particularly to a refrigerator with differenttemperature compartments in which no frost is allowed to accumulate.

An object of this invention is to provide a refrigerator having a belowfreezing compartment and an above freezing compartment in which no frostis allowed to accumulate in either compartment or on the foods containedtherein.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred form of the invention is clearly shown.

In the drawings:

Figure l is a vertical cross-section taken along the line 1-1 of Figure2.

Figure 2 is a vertical cross-section transverse to Figure 1 taken alongthe line 2-2 ofFigure 1 with parts broken away.

Figure 3 is a vertical cross-section of a portion of Fig ure 1 takenalong the line 33 of Figure 1.

Figure 4 is a diagrammatic representation of the re-- frigeratingsystem.

Figure 5 is a partial view of Figure 1, showing a part in a differentposition.

Figure 6 is a vertical cross-section taken along the line 6-6'of Figure1.

Figure 7 is an enlarged crosssection of a portion of Figure l.

Figure 8 is a view in perspective of the below freezing compartment.

Figure 9 is a wiring diagram for the apparatus of Figures 1' through 8.

Figures 10 and 1-1 show a portion of Figure 9 in different positions.

A refrigerator, according to this invention, has a below freezingcompartment and a refrigerating, above freezing, compartment Zl. Arefrigeration system is provided, including a refrigerant evaporator 22and a refrigerant liquefier in refrigerant circulating relationship withthe evaporator 22. The liquefier may include a motor compressor unit 23and a condenser 24. The liquefied refrigerant flows through theexpansion valveor capillary tube 25 to the evaporator 22 and returnsthrough the conduit 26 to the motor compressor unit 23.

If desired, the evaporator 22 may include an accumulator 27 to trapliquid refrigerant and prevent the return of slugs to the compressor 23.

Air circulating means, in the form of one or more blowers 3 3, isprovided. Conduit means for circulating air may include the up Howconduit 31 leading to the serpentine conduits 32 around the belowfreezing compartment 20. These serpentine conduits 32 discharge air intothe compartment 20 through openings 33. The air from compartment 20returns through openings 34 into the front, surrounding conduit 34a, andthe horizontal, rearwardly directed flow conduit 34b, which dischargesinto the down flow conduit 35. The conduit 35 is in 2,792,691 PatentedMay 21, 1957 thermal exchange with the above freezing compartment 21.The conduit 35 returns the air to the air circulating means or blowers30.

The thermal exchange between the down flow conduit 35 and thecompartment 21 may be through an insulated wall 36 having a thicknesssufiicient to reduce the temperature in compartment 21 substantially tothe tempera ture desired under normal operating conditions. Theevaporator 22 is placed in the down fiow conduit 35, and preferably isin the form of vertical runs 37 joined by 180 bends 38 and 39. Theevaporator 22 is placed a small distance from the insulated wall 36.

The circulated air is chilled by the evaporator 22 to a temperaturebelow that to be maintained in compartment 24 Hence, the frostdepositing temperature of the circulated air is also below thetemperature in compartment 20. Frost is deposited only on evaporator 22,and none is allowed to accumulate in either compartment 20 orcompartment 21. These compartments never need defrosting, and theperiodic defrosting of evaporator 22 has practically no effect on thefood temperatures in these compartments. Any frost which mightmomentarily form on the cold surfaces in the freezing compartment whenthe freezing compartment door is opened is quickly removed by theprocess of sublimation when the door is closed.

Means are provided for periodically defrosting the evaporator 22 andthis may take the form of a serpentine electric heater 40 in thermalexchange with the lower part of the evaporator 22. The heater 40 isenergized periodically under the control of a timer hereafter described.

Means are provided for varying the thermal exchange of the circulatedair with the above freezing compartment 21. This may take the form of adamper which is moved rightward or leftward by the linkage 46 connectedto a thermostat 47 responsive to the temperatures in the compartment 21.As the temperature in compartment 21 falls, the linkage 46 moves thedamper 45 rightward and vice versa. The action of this construction isto maintain the temperature in compartment 21 within desired limitsnotwithstanding varying conditions of operation.

A defrost timer is provided having a motor 50 and a cam 51. The cam 51has a large smooth cam surface 52 establishing a refrigerating periodand a relatively small notch 53 establishing a defrost period. A pivotedfollower 54 is fulcrumed at 55 and is urged upwardly by the upwardlybiased contact blade 56 having double contacts 57. In general, when thesmooth surface 52 engages the follower 54, a refrigerating period isestablished to permit the refrigerating system to produce refrigerationand the air circulating means to operate. In general, when the notch 53is in engagement with the follower 54, a defrosting period isestablished which stops the refrigerating system from producingrefrigeration, stops the air circulating means, and causes operation ofthe defrosting means. in addition, means are provided for changing thetimer switch from a defrost position to a refrigeration position whenthe evaporator 22 has been defrosted prior to the expiration of thetimed defrosting period, as will be more fully explained.

The air circulating means or blowers 3d are driven by one or more motors69. A thermostatic bulb 61 is placed near the discharge end of theevaporator 22 and is connected to a bellows 62 which opens and closesthe switch 63 as the temperatures in the evaporator 22 fall and riserespectively. The thermostatic bulb 61 tends to maintain the evaporatortemperature at a substantially constant temperature withinpredetermined. limits below the temperature selected for the compartment20 by controlling the operation of the motor compressor 23. To this end,the thermostat 61, 62, 63 is responsive to evaporator temperatures andprevents operation of the motor compressor 23 when the temperature ofthe evaporator is below a predetermined low temperature and permitsoperation of the motor compressor when the temperature of saidevaporator is above said low temperature.

Means are provided to terminate the defrost period when the defrostingoperation has been completed even while the timer notch 53 is still inengagement with the follower 54. To this end, a thermostatic bulb 7% isplaced in thermal exchange with the evaporator 22, preferably at theupper return bends 39 (Figure 4). The bulb 70 is connected to a bellows71 which operates the lever 72 fulcrumed at 73. The thermostat 7d, 71and 72 has means automatically changing the defrost switch position ofthe timer into a refrigerating switch position in response to apredetermined high temperature in the evaporator 22, acting on thethermostatic bulb 7%. This is accomplished by providing a pair ofupwardly biased contact blades 75 and 76 (Figures 9, and ll) tiedtogether by the insulating spacer 77, and by providing a tongue 78adapted to cooperate with the detent 79 of lever 72.

During the refrigerating period, as shown in Figure 11, thecircumference 52. of cam 51 moves the follower 54 downward, to causeblade 56 also to be moved downward. The double contacts 57 engage thecontact Sil of the blade 76 and thus force both of the blades 75 and 76downward causing the tongue 78 to be engaged by the detent 79, and thisholds the timer circuit and its blades to provide electrical energy fromline L to the refrigerator line Ml to provide refrigeration throughoutthe normal refrigerating period.

When the defrost period begins, as indicated in Figure 10, the notch 553permits the follower 54 to rise upwardly, allowing the upwardly biasedblade 56 to engage the contact 81 of the blade 75 and to urge the blades75 and 76 upwardly, in readiness to snap upwardly when permitted to doso as later described. In the position of Figure 10, refrigeration isstopped by the opening of contacts 57 and 8t), and defrosting isproduced by the closing of contacts 57 and 81, which energize thedefrost heater 40 from line L through contacts 57, 81, blade 75, line75a, heater 40 and line L1.

Figure 9 shows the termination of the defrost period and start of therefrigerating action. To this end, when all of the frost has beenmelted, the heater 463 is deenergized and the refrigeration cycle isstarted even if notch 53 is still engaging the follower 54, because thetemperature of the evaporator 22 rises under the heating action of theheater 40 as soon as the frost is completely melted. The thermostaticbulb 7t then acts on the bellows 71. to move the pin 82 rightward inFigure 9 and upward in Figure 4 and to rotate the lever 72 clockwiseabout the fulcrum '73 against the action of spring 83. This releases thetongue 78 from the detent 79 (from the position of Figure 10) and allowsthe blades 75 and 76 to move upward to the position shown in Figure 9where the double contacts 57 engage the contact 80 of the blade 76 toestablish refrigerating conditions by energizing the air circulatingmotors 6t) and permitting operation of the motor compressor unit 23through the medium of thermostatic switch 63 and starting relay 85. Theaction taking place in Figure 9 changes the defrost period which hadpreviously been established, as in Figure 10, to a refrigeration periodduring the unexpired portion of the timed defrost period produced by thenotc 53. When the timer cam 51 rotates beyond the engagement of thenotch 53 and enters into the smooth portion 52 of the cam as shown inFigure l], the regular refrigeration cycle is resumed as previouslydescribed with respect to Figure ll.

During the defrosting operation, any moisture melted from the evaporatorfalls to the bottom of conduit 35 and flows through the pipe 86 to thepan 87 immediately CPL over the condenser 24, where the moisture isevaporated. Any moisture which is condensed on the cold walls of thecompartment 21 falls to the sloping bottom 88 of compartment 21, andflows through the pipe 89 to the pan 87 also to be evaporated therein.

In the operation of the refrigerator, the motor compressor 23 ordinarilyis cycled under the control of thermostat 61, 62, 63, with the timer inthe position shown in Figure 11. Power flows from the line L to theblade 56 and thence to the blade 76 to the line 90 from which currentflows through the switch 63 (Figure 9) and relay 35 to the motorcompressor 23, which operates in the usual manner to maintain theevaporator 22 within predetermined limits established by the thermostatbulb 61. At the same time, the line 96 energizes the blower motors 6d tocause circulation of air through the conduits 31 through 35. The airflowing down through conduit 35 is refrigerated to a temperature belowthat maintained in compartment 20 and thus has its moisture contentreduced to a frost depositing temperature below that of compartmerit 20.So, when the air circulates into the compartment 21?, it does notdeposit any frost therein, but at the same time maintains thecompartment below a freezing temperature, since the air flows around thecompartment 2t and through it, and then returns through the down flowconduit 35. The air is sufficiently cold to refrigerate the compartment21 to the proper degree through the thermal exchange of the wall 36 asvaried by the action of baffle 45 to maintain the temperature ofcompartment 21 above freezing, but at the suitable refrigeratingtemperature established by the thermostat 47. This operation continuesas long as the smooth circumference 52 of the timer cam 51 establishes arefrigerating period as shown in Figure 11.

When the timer establishes a defrosting period as shown in Figure 10,the notch 53 allows the follower 54 to rise and permit the blade 56 tomove and bias the blades 75 and 76 upward. During the defrost operationas shown in Figure 10, current flows from the line L through the blades56 and 75 and line 75a to the defrost heater 44 so that the evaporator22 is heated to a defrosting temperature.

When substantially all of thefrost has been removed from the evaporator22, it is heated to a predetermined high temperature. The thermostat 70,71 and 72 then rotates the lever 71?. clockwise to the position shown inFigure 9, at which time the defrost switch position is changed into arefrigerating position during the unexpired portion of the timed defrostperiod. Refrigeration is produced by current flowing from L throughcontacts 80 and 57 to the compressor 23 and blowers 60, through line 90.

The compartment 20 is maintained at a below freezing temperature and thecompartment 21 is maintained at a predetermined refrigerating, abovefreezing, temperature without the formation of frost within thecompartment 2% or on the food contained therein. Any moisture condensedon the rear wall of compartment 21 flows down such wall and isdischarged through pipe 89 as previously described. Thus, a completelyautomatic defrosting refrigerator is provided.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted as may come within the scope of the claims whichfollow.

What is claimed is as follows:

1. In combination: a below freezing compartment; a refrigerating abovefreezing compartment; a refrigeration system including an evaporator anda refrlgerant liquefier in refrigerant circulating relationship; aircirculating means; conduit means for circulating air from said aircirculating means in thermal exchange with said evaporator, into saidbelow freezing compartment, and adjacent and in thermal exchange withsaid above freezing compartment; defrosting means for defrosting saidevaporator; and a timer having a defrost. period and. a refrigeratingperiod and stopping. said refrigerating system from producingrefrigeration, stopping saidv air circulating means and causingoperation of said defrosting means during said defrosting period, andpermitting said refrigerating system to produce refrigeration and saidair circulating means to operate and stop said defrosting means duringsaid refrigerating period.

2. In combination: a below freezing compartment; a refrigerating abovefreezing compartment; a refrigeration system including an evaporator anda refrigerant liquefier in refrigerant circulating relationship; aircirculating means; conduit means for circulating air from said aircirculating means in thermal exchange with said evaporator, around andinto said below freezing compartment, and adjacent and in thermalexchange with said above freezing compartment; defrosting means fordefrosting said evaporator; and a timer having a defrost period and arefrigerating period and stopping said refrigerating system fromproducing refrigeration, stopping said air circulating means and causingoperation of said defrosting means during said defrosting period, andpermitting said refrigerating system to produce refrigeration and saidair circulating means to operate and stop said defrosting means duringsaid refrigerating period.

3. In combination: a below freezing compartment; a refrigerating abovefreezing compartment; a refrigeration system including an evaporator anda refrigerant liquefier in refrigerant circulating relationship; aircirculating means; conduit means for circulating air from said aircirculating means in thermal exchange with said evaporator, into saidbelow freezing compartment, and adjacent and in thermal exchange withsaid above freezing compartment; defrosting means for defrosting saidevaporator; means for varying the thermal exchange of said circulatedair with said above freezing compartment; and a timer having a defrostperiod and :a refrigerating period and stopping said refrigeratingsystem from producing refrigeration, stopping said air circulating meansand causing operation of said defrosting means during said defrostingperiod, and permitting said refrigerating system to producerefrigeration and said air circulating means to operate and stop saiddefrosting means during said refrigerating period.

4. In combination: a below freezing compartment; a

circulating means in thermal exchange with said evaporator, into saidbelow freezing compartment, and adjacent and in thermal exchange withsaid above freezing compartment; defrosting means for defrosting saidevaporator; means for varying the thermal exchange of said circulatedair with said above freezing compartment in response to temperatures insaid above freezing compartment; and a timer having a defrost period anda refrigerating period and stopping said refrigerating system fromproducing refrigeration, stopping said air circulating means and causingoperation of said defrosting means during said defrosting period, andpermitting said refrigerating system to produce refrigeration and saidair circulating means to operate and stop said defrosting means duringsaid refrigerating period.

5. In combination: a below freezing compartment; a refrigerating abovefreezing compartment; a refrigeration system including an evaporator anda refrigerant liquefier in refrigerant circulating relationship; aircirculating means; conduit means for circulating air from said aircirculating means in thermal exchange with said evaporator, into saidbelow freezing compartment, and adjacent and in thermal exchange withsaid above freezing compartment; defrosting means for defrosting saidevaporator; a thermostat responsive to evaporator temperaturespreventing operation of said liquefier when the temperature of saidevaporator is below a. predetermined low temperature and permittingoperation of. said liquefier when the temperature of said evaporator isabove said low temperature; and a timer having a defrost period and arefrigerating period and stopping said refrigerating system fromproducing refrigeration, stopping said air circulating means and causingoperation of said defrosting means during said defrosting period, andpermitting said refrigerating system to produce refrigeration and saidair circulating means to operate and stop said defrosting means duringsaid refrigerating period.

6. In combination: a below freezing compartment; a refrigerating abovefreezing compartment; a refrigeration system including an evaporator anda refrigerantliquefier in refrigerant circulating relationship; aircirculating means; conduit means for circulating air from said aircirculating means in thermal exchange with said evaporator, into saidbelow freezing compartment, and adjacent and in thermal exchange withsaid above freezing compartment; defrosting means for defrosting saidevaporator; a timer having a defrost period and .a refrigerating periodand stopping said refrigerating system from producing refrigeration,stopping said air circulating means and causing operation of saiddefrosting means during said defrosting period, and permitting saidrefrigerating system to produce refrigeration :and said air circulatingmeans. to operate and stop said defrosting means during saidrefrigerating period; and a thermostat automatically changing saiddefrost period into refrigerating period in response to a predeterminedhigh temperature.

7. In combination: a below freezing compartment; a

refrigerating above freezing compartment; a refrigeration systemincluding an evaporator and a refrigerant liquefier in refrigerantcirculating relationship; air circulating means; conduit means forcirculating air from said air circulating means in thermal exchange withsaid evaporator, into said below freezing compartment, and adjacent andin thermal exchange with said above freezing compartment; defrostingmeans for defrosting said evaporator; a timer having a defrost periodand a refrigerating period and stopping said refrigerating system fromproducing refrigeration, stopping said air circulating means and causingoperation of said defrosting means during said defrosting period, andpermitting said refrigerating system to produce refrigeration and saidair circulating means to operate and stop said defrosting means duringsaid refrigerating period; and a thermostat automatically changing saiddefrost period into refrigerating period in response to a predeterminedhigh temperature of said evaporator.

8. In combination: a below freezing compartment; a refrigerating abovefreezing compartment; a refrigeration system including an evaporator anda refrigerant liquefier in refrigerant circulating relationship; aircirculating means; conduit means for circulating air from said aircirculating means in thermal exchange with said evaporator, into saidbelow freezing compartment, and adjacent and in thermal exchange withsaid above freezing compartment; defrosting means for defrosting saidevaporator; and a control means establishing a defrost period and arefrigerating period and stopping said refrigerating system fromproducing refrigeration, stopping said air circulating means and causingoperation of said defrosting means during said defrosting period, andpermitting said refrigerating system to produce refrigeration and saidair circulating means to operate and stop said defrosting means duringsaid refrigerating period.

9. In combination: a below freezing compartment; a refrigerating abovefreezing compartment; a refrigeration system including an evaporator anda refrigerant liquefier in refrigerant circulating relationship; aircirculating means; conduit means for circulating air from said aircirculating means in thermal exchange with said evapora' tor, around andinto said below freezing compartment, and adjacent and in thermalexchange with said above freezing compartment; defrosting means fordefrosting said evaporator; and a control means establishing a defrostperiod and a refrigerating period and stopping said refrigerating systemfrom producing refrigeration, stopping said air circulating means andcausing operation of said defrosting means during said defrostingperiod, and permitting said refrigerating system to produce refrigeration and said air circulating means to operate and stop said defrostingmeans during said refrigerating period.

10. In combination: a below freezing compartment; a refrigerating abovefreezing compartment; a refrigeration system including an evaporator anda refrigerant liquefier in refrigerant circulating relationship; aircirculating means; conduit means for circulating air from said aircirculating means in thermal exchange with said evaporator, into saidbelow freezing compartment, and adjacent and in thermal exchange withsaid above freezing compartment; defrosting means for defrosting saidevaporator; a control means establishing a defrost period and arefrigerating period and stopping said refrigerating system fromproducing refrigeration, stopping said air circulating means and causingoperation of said defrosting means during said defrosting period, andpermitting said refrigerating system to produce refrigeration and saidair circulating means to operate and stop said defrosting means duringsaid refrigerating period; and a thermostat automatically changing saiddefrost period into refrigerating period in response to a predeterminedhigh temperature of said evaporator.

11. In combination: a casing having an outer shell; insulation disposedadjacent said outer shell; means forming a hollow wall inner shellconstituting a below-freezing compartment Within said outer shell; meansforming an above-freezing compartment within said outer shell; arefrigerating system including evaporator means and a refrigerantliquefier in refrigerant circulating relationship; means for circulatingair in thermal exchange with a portion of said evaporator means andthereafter through portions of the hollow walls of said below-freezingcompartment; means for directing the air leaving said hollow Walls intosaid below-freezing compartment; said evaporator means including aportion arranged in thermal exchange relationship With air for saidabove-freezing compartment; defrosting means for defrosting saidevaporator means; and means for cyclically energizing said evaporatordefrosting means; said last-named means including means for stopping theflow of air into said freezing compartment during the defrosting of saidevaporator means.

12. In combination: a casing having an outer shell; insulation disposedadjacent said outer shell; means forming a hollow wall inner shellconstituting a below-freezing compartment within said outer shell; meansforming an above-freezing compartment within said outer shell; arefrigerating system including evaporator means and a refrigerantliquefier in refrigerant circulating relationship; means for circulatingair in thermal exchange with a portion of said evaporator means andthereafter through portions of the hollow walls of said below-freezingcompartment; means for directing the air leaving said hollow Walls intosaid below-freezing compartment; said evaporator means including aportion arranged in thermal exchange relationship With air for saidabove-freezing compartment; defrosting means for defrosting saidevaporator means; and means for cyclically energizing said evaporatordefrosting means; said last-named means including means for stopping thefiow of air into said freezing compartment during the defrosting of saidevaporator means; said evaporator means comprising a unitary evaporatorfor cooling both of said compartments.

References Cited in the file of this patent UNITED STATES PATENTS2,180,974 Atchison et al Nov. 21, 1939 2,310,117 Reeves Feb. 2, 19432,346,837 Grooms Apr. 18, 1944 2,458,048 Bauman Jan. 4, 1949 2,467,427Green Apr. 19, 194-9 2,561,276 Hill July 17, 1951 2,687,620 Raney Aug.31, 1954 2,690,526 Morrison Sept. 28, 1954 2,711,456 Goodhouse et a1June 21, 1955

